Today, email addresses are trivial to forge. When an email is received with a sender address of, say, yourBigBoss@yourcompany.example.com there is virtually no way to verify that that email actually came from the person authorized to use that sender address.
Spammers take tremendous advantage of this ability to forge and fake email addresses. Forging and faking email addresses is now so rampant that a good number of email system administrators simply block all email from popularly forged domains, e.g., hotmail.com, msn.com, and yahoo.com, because these email administrators have no way of distinguishing real email from forged email.
This sort of haphazard blocking strategy is now widely deployed across the Internet as email administrators desperately try and deal with the rising flood of spam. Unfortunately, these desperation tactics negatively impacts the benefits of email.
However, if a domain owner could irrefutably determine whether an email legitimately originated from the authorized user of a particular email address or not, then recipient email systems can apply filtering and acceptance policies much more rigorously and accurately without much of the negative impact of the current, relatively arbitrary, methods. Thus, it is with respect to these considerations and others that the present invention has been made.